Nowadays, computers are widely used and become essential parts in our daily lives. In addition to the working purposes, computers may be employed as amusement tools. With increasing development of computers, computer peripheral devices make great progress. Moreover, input devices play important roles in communicating computers and user. As known, a keyboard device is one of the most important input devices. Consequently, the manufacturers of keyboard device make efforts in designing novel keyboard devices with special functions in order to meet the requirements of different users.
Generally, a keyboard device comprises plural key structures. Hereinafter, a conventional key structure will be illustrated with reference to FIGS. 1 and 2. FIG. 1 is a schematic exploded view illustrating a conventional key structure. FIG. 2 is a schematic side view illustrating the conventional key structure of FIG. 1, in which the keycap is not depressed. As shown in FIGS. 1 and 2, the conventional key structure 1 comprises a keycap 11, a scissors-type connecting member 12, a rubbery elastic element 13, a membrane switch circuit board 14, and a base plate 15. The keycap 11 may be depressed by a user. In addition, the keycap 11 is connected with the scissors-type connecting member 12. The keycap 11 comprises a first fixing structure 111 and a second fixing structure 112. The first fixing structure 111 is disposed on a bottom surface 113 of the keycap 11, and located at a first side of the keycap 11. The second fixing structure 112 is disposed on the bottom surface 113 of the keycap 11, and located at a second side of the keycap 11. The base plate 15 comprises a third fixing structure 151 and a fourth fixing structure 152. The third fixing structure 151 is disposed on the base plate 15, and located at a first side of the base plate 15. The fourth fixing structure 152 is disposed on the base plate 15, and located at a second side of the base plate 15. The first fixing structure 111 and the third fixing structure 151 are close-type hooks, and the second fixing structure 112 and the fourth fixing structure 152 are open-type hooks.
The scissors-type connecting member 12 comprises an inner frame 121 and an outer frame 122. A first end of the inner frame 121 is connected with the first fixing structure 111 of the keycap 11. A second end of the inner frame 121 is connected with the fourth fixing structure 152 of the base plate 15. A first end of the outer frame 122 is connected with the third fixing structure 151 of the base plate 15. A second end of the outer frame 122 is connected with the second fixing structure 112 of the keycap 11. Consequently, the scissors-type connecting member 12 is connected with the keycap 11 and the base plate 15. The inner frame 121 has an inner frame shaft 1211. The outer frame 122 has an outer frame hole 1221 corresponding to the inner frame shaft 1211. After the inner frame shaft 1211 is inserted into the outer frame hole 1221, the inner frame 121 and the outer frame 122 are combined together. Consequently, the inner frame 121 is rotatable relative to the outer frame 122. The membrane switch circuit board 14 is disposed on the base plate 15. The rubbery elastic element 13 is arranged between the keycap 11 and the membrane switch circuit board 14. When the keycap 11 is depressed, the rubbery elastic element 13 is pushed by the keycap 11 and thus subject to deformation. Consequently, the membrane switch circuit board 14 is triggered to generate a key signal. After the above components are combined together, the assembled configuration of the key structure 1 is shown in FIG. 2.
Hereinafter, the operations of the conventional key structure 1 will be illustrated with reference to FIGS. 2 and 3. FIG. 3 is a schematic side view illustrating the conventional key structure of FIG. 1, in which the keycap is depressed. In case that the key structure 1 is not depressed (see FIG. 2), the keycap 11 of the key structure 1 is located at a first height H1. Meanwhile, the inner frame 121 and the outer frame 122 intersect each other, so that the scissors-type connecting member 12 is in an open-scissors state. In addition, the second end of the outer frame 122 is located at a first position P1 of the second fixing structure 112. Whereas, when the key structure 1 is depressed, a downward pressing force is exerted on the keycap 11, and the rubbery elastic element 13 is compressed in response to the pressing force. Moreover, as the keycap 11 is depressed, the inner frame 121 and the outer frame 122 of the scissors-type connecting member 12 are correspondingly rotated by using the inner frame shaft 1211 and the outer frame hole 1221 as the rotating shaft. Meanwhile, the inner frame 121 and the outer frame 122 are is in a folded state. At the same time, the membrane switch circuit board 14 on the base plate 15 is pressed and triggered to generate a corresponding key signal. Moreover, as shown in FIG. 3, the keycap 11 of the key structure 1 is located at a second height H2, and the second end of the outer frame 122 is moved to a second position P2 of the second fixing structure 112. Generally, the difference between the first height H1 and the second height H2 indicates a travelling distance of the key structure 1.
In case that the keycap 11 is no longer depressed, the keycap 11 will be moved upwardly is response to a restoring force of the compressed rubbery elastic element 13. As the keycap 11 is moved upwardly, the inner frame 121 and the outer frame 122 are towed by the keycap 11 and correspondingly rotated. Consequently, the keycap 11 is moved to the first height H1, and the second end of the outer frame 122 is returned to the first position P1 of the second fixing structure 112.
However, the conventional key structure 1 still has some drawbacks. For example, as the computer has been used for a long time, the user is readily suffered from finger fatigue or even finger injury because of frequently depressing the key structure 1.
Therefore, there is a need of providing a labor-saving key structure in order to solve the above drawbacks.